A concept of light connection (Light Connection) is proposed in the 3rd Generation Partnership Project (3rd Generation Partnership Project, “3GPP” for short) Release 14 (Release 14). A network device may instruct a terminal device to enter a light connected mode from a radio resource control (Radio Resource Control, “RRC” for short) connected mode. After entering the light connected mode, the terminal device hides a status of the terminal device from a core network device in other words, the core network device does not know the status of the terminal device. When downlink data arrives, the core network device still processes the downlink data based on an assumption that the terminal device is in the connected mode, and sends the downlink data to an access network device (for example, a base station) to which the terminal device is connected last time. When the downlink data arrives at the access network device, the access network device may be triggered to initiate paging on the terminal device, to wake up the terminal device, thereby completing downlink data transmission.
In the prior art, a terminal device in an idle (idle) mode monitors a physical downlink control channel (Physical Downlink Control Channel, “PDCCH” for short) in a specific subframe (namely, a paging frame (Paging Frame, “PF” for short)). If a paging message is indicated on the PDCCH channel, the terminal device demodulates a paging channel (Paging Channel, “PCH” for short) to determine whether the paging message belongs to the terminal device. The PF is obtained through calculation based on a discontinuous reception (Discontinuous Reception, “DRX” for short) cycle. Each terminal device has a dedicated discontinuous reception (Discontinuous Reception, “DRX” for short) cycle and a unique identifier (for example, an international mobile subscriber identity (International Mobile Subscriber Identity, “IMSI” for short)).
Therefore, when the access network device receives the downlink data sent by the core network device, how to effectively page the terminal device is a technical problem that needs to be urgently resolved.